Leading an engaged lifestyle through midlife and older age has been associated with maintaining physical health, well-being, and cognitive functioning. Although these findings highlight the importance of activity engagement to health outcomes, few studies have investigated how changes in health influence the activities older adults pursue. As life expectancy increases, the prevalence of chronic disease has become more common; thus, there is a growing need to understand how older adults cope and adapt to changes in their health. Activity engagement may have implications for the course of the disease, future health outcomes, and quality of life, making understanding how specific chronic health conditions influence the longitudinal trajectories of time use in older adulthood an important question. Previous research on activity engagement has focused exclusively on the individual, but activities occur in a social context and are frequently engaged with one's spouse. Adjustment to changes in health also occurs in a social context, most particularly within marital relationships. The experience of chronic illness is often shared between a patient and their spouse; thus, older couples likely adjust the ways in which they allocate their time in response to their own health as well as their partners' health. The overarching goal of this application is o examine longitudinal associations between chronic illness and activity engagement in the context of married couples. We propose using 5 waves of biennial longitudinal time use and health data from a nationally representative sample of middle aged and older married couples 51 years of age and older in the Health and Retirement Study (HRS). We will link health data obtained from the core HRS survey to time use data from an off-wave survey, the Consumption and Activities Mail Survey (CAMS). CAMS surveys a diverse scope of activities, allowing for a more granular study of activity engagement. We focus our analyses on two prevalent age-related chronic illnesses, arthritis and cardiovascular disease, and ask how these diseases and changes in severity impact activity engagement over time. The longitudinal nature of the data enables us to treat diagnosis as a time-varying predictor, further allowing us to compare trajectories of activity engagement for couples who never develop the disease to those where one or both partners eventually do. We additionally address how caregiving for a spouse impacts active engagement over time. Caregiving stress has been linked to poorer physical and psychological well-being and the time demands inherent to the role may result in reallocating time from activities that promote health and well-being to caregiving. This project will bring a much needed dyadic perspective to activity engagement by highlighting how activity changes in response to both partners' health over time. The findings from this work have implications for interventions seeking to preserve or improve well-being and active engagement in older couples.